Influência do clareamento dentário de consultório na dureza superficial de resinas compostas: um estudo in vitro

Abstract

The study aimed to evaluate the surface hardness of three composite resins (Filtek Z350 - 3M ESPE, Zirconfil - TECHNEW, Vitra - FGM), after an in-office tooth whitening process using 40% hydrogen peroxide. Sixty specimens were made, with thicknesses of 6.0 x 2.0 mm, with 20 specimens of each restorative material (n=20). After finishing and polishing, the specimens were randomly divided into two groups for each restorative material (n=10), where the control group G1-C was maintained in artificial saliva and the experimental group G2-E was subjected to gel in-office bleaching agent based on 40% hydrogen peroxide, according to the manufacturer's instructions. The hardness test used was the Vickers hardness test and for each specimen, four consecutive and equidistant readings were performed, with a load of 300g of force for 15s. Hardness values for tested resins were statistically higher in the control group than in the test group. The greatest difference in mean values between the groups occurred in the Z350XT resin and for the fixed margin of error (5%) there is a significant difference (p < 0.05) between the test and control groups for each resin. The use of 40% hydrogen peroxide by the in-office technique promoted significant changes in the surface hardness of the tested resins. In addition, the Z350XT resin presented higher hardness than the other resins, but was the most affected by the bleaching agent.